Recent questions tagged c++

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c++ - Why does in_avail() output zero even if the stream has some char?

#include <iostream> int main( ) { using namespace std; cout << cin.rdbuf()->in_avail() << endl; cin.putback(1) ... 12; it still outputs 0 and 0 See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to use fgets if you don't know the number of characters to be read?

I need to read a file and send the text from it to a string so I can parse it. However, the program won't ... *str, size_t num, FILE *stream); See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - how to find which process has a handle on a file from the file name

Is there anything in the Windows c++ API to give me a list of processes that have a handle to a given file? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Density of floating point number - Magnitude of the number

Is it true that the more the floating point number is big (either positive or negative) the less we have ... values between this two ranges? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Mismatch of 'this' address when base class is not polymorphic but derived is

There is this code: #include <iostream> class Base { public: Base() { std::cout << "Base: " << this ... is not polymorphic and Derived class is? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Passing std::array as arguments of template variadic function

I am trying to learn about variadic templates in C++11. I have a class which is basically a wrapper around a ... and pass in a lambda directly? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why does std::move take a forward reference?

The implementation of std::move basically looks like this: template<typename T> typename std::remove_reference<T>: ... both lvalues and rvalues? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How much performance difference when using string vs char array?

I have the following code: char fname[255] = {0} snprintf(fname, 255, "%s_test_no.%d.txt", baseLocation, i); ... any better way to do this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to detect global key sequence press in Qt?

I want to detect whether a key sequence is pressed and want to perform certain task on that event in Qt. ... hidden. How to solve this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is the order of initialization guaranteed by the standard?

In the following code snippet d1's initializer is passed d2 which has not been constructed yet (correct?), ... initialization of data members? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How would you transpose a binary matrix?

I have binary matrices in C++ that I repesent with a vector of 8-bit values. For example, the following ... that can only handle certain sizes. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Example of increasing the work per thread in CUDA

Algorithm : I'm writing a program with CUDA and the problem is the following: Two matrices A (n * 128) and ... GTX 650 (compute capability 3.0) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Copy Constructor Needed with temp object

The following code only works when the copy constructor is available. When I add print statements (via std::cout) and make ... call to N::N(N)' See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Can objects with private copy constructors be thrown?

I've come across some exceptions issue that is unclear to me. In C++, when an object is thrown it is first ... return 0; } Is this legal? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Debug through libstdc++

I'm using gcc on GNU/Linux and the debug-files and headers of libc and libstd++ are installed. But I don' ... .h in the completely wrong place? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Are compilers allowed to optimize-out exception throws?

We have been discussing this topic today at work, and none of us could come up with a definitive answer ... construction has no side effect) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Pretty-print types and class template along with all its template arguments

Since typeid(T).name() doesn't return human understandable name of the type, it doesn't help us much ... template and its arguments generically? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How do you check for an invalid pointer?

My current code to the effect of: if( objectPointer != NULL){ delete objectPointer; } doesn't work because the ... trying to delete the object? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - redirect output of an function printing to console to string

lets say we have a function which prints text to the console and in which we do not have control over the ... way to do this via terminal See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - More than 1 address for derived class object?

In Item 27 of "Effective C++" (3rd Edition, Page 118), Scott Meyers said: class Base { ... }; class ... is implemented in the C++ compiler? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - RANSAC-like implementation for arbitrary 2D sets

TL;DR : Is there a C++ implementation of RANSAC or other robust correspondence algorithms that is freely usable with ... that I have missed... See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Lifetime of rvalue reference

I think I have a problem with understanding rvalue references. What is really the lifetime and usage of such ... the new lifetime of object? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Do parentheses force order of evaluation and make an undefined expression defined?

I was just going though my text book when I came across this question What would be the value of a after the ... clear answer will get my vote See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Design Pattern, Qt Model/View and multiple threads

I am creating an application which displays the market data and uses it in some other forms too. I store ... /ill-formed questions. Thanks Shiv See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - "Avoid returning handles to object internals", so what's the alternative?

Effective C++ by Scott Meyers tells in Chapter 5, Item 28 to avoid returning "handles" (pointers, references or ... do you handle such cases? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Output difference in gcc and turbo C

Why is there a difference in the output produced when the code is compiled using the two compilers gcc and turbo c ... " on turbo c. Why? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Error: pure virtual method called - terminate called without an active exception - Aborted

In my A.h file: class A{ private: unsigned short PC; public: A():PC(0){} virtual ~A(){} ... anybody where did I misunderstand? Thank you See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is it possible to use boost accumulators with vectors?

I wanted to use boost accumulators to calculate statistics of a variable that is a vector. Is there a simple way to do ... I'm a bit dumb. :P See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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